RUMEN boluses have long been maligned in the choice of identification devices under the National Livestock Identification System.

Boluses are small ceramic or plastic capsules inserted down the throat to rest at the front of the rumen, and with almost total retention offer more secure identification than ear tags.

The vast majority of producers across the country have chosen ear tags for several reasons, including a perceived cost benefit.

Rumen boluses now cost the same as an ear tag and can be re-used. Processors have been reluctant to retrieve the boluses from the dead beast, but new trial results are showing the benefits could significantly outweigh the costs at some plants if more boluses were used.

A 12-month trial was conducted at the Norvic Food Processing plant at Wodonga, Victoria, where 360 head are slaughtered each day at a rate of 41 an hour.

The trial showed the $61,500 cost of installation could be recouped in less than a year if all cattle killed were fitted with boluses. When water savings are factored, the investment could be recovered in eight months.

This would rely on a major change to current practice as only one per cent of cattle killed by Norvic carry boluses.

They are already approved devices under NLIS, in conjunction with a matching management ear tag which carries the same NLIS number.

The widespread adoption of boluses has been stalled by processor objections that boluses damaged equipment or were too costly to separate from paunch material.

Meat and Livestock Australia (MLA) was commissioned by the Australian Meat Industry Council to find a way to retrieve rumen boluses without additional costs.

MLA's NLIS manager, Mick Prendergast, said the technical information from the trial would be made available to processors, but the decision to implement it would be the commercial decision of individual abattoirs.

"AMIC wanted us to demonstrate how it could be done with no added labour or water, and we believe those issues have been technically addressed in this report," Mr Prendergast said.

Norvic previously 'wet-dumped' paunch contents as part of its effluent stream used plenty of water and also failed to recover a range of other contaminants swallowed by cattle.

In the trial system, paunch material was first pushed through an auger to squeeze out excess moisture then shaken on a vibrating screen to separate contaminants, including boluses.

There were no additional labour requirements, with existing staff emptying paunch bins and collecting and sorting the much larger range of contaminants removed, ranging from string and baling twine to cobalt capsules, plastic bags and rocks.

Despite some marking of the outside surface, boluses were not damaged during the process and there was initially an 88 percent recovery rate, of which 100pc were readable.

After modification, this lifted to 100pc recovery and complete readability, meaning manufacturers could resurface and recycle all boluses, bringing prices down.

Only 1pc of the cattle Norvic processes are fitted with a bolus, and although the devices are currently being returned to the manufacturer at no charge, they are estimated to have a commercial value of about $1 each.

The trial report said if bolus use was mandated or driven by commercial demand to include the 360 head a day killed at the plant, working on a recovery rate of 95pc, the value of the recovered boluses would be $340 a day, or $81,600 a year.

Water use would drop by about 40 litres a minute, or 192 kilolitres a week.

Since water costs Norvic 53kl and there is a $1.16kl charge for effluent to the sewer system, this would mean a saving of almost $17,000 a year.

Secondary uncosted benefits include reduced maintenance and higher quality meat and bone meal and compost, thanks to the removal of far more contaminants which would have become blocked in effluent screening or ended up in rendering or composting equipment.

The new system also reduces the amount of nutrients including nitrogen and phosphorous in the processor's effluent stream.